chromium/third_party/blink/web_tests/animations/interpolation/svg-stroke-opacity-interpolation.html

<!DOCTYPE html>
<meta charset="UTF-8">
 <style>
.parent {
  stroke-opacity: 0.8;
}
.target {
  display: inline-block;
  fill: none;
  stroke: black;
  stroke-width: 50px;
  stroke-opacity: 0.6;
}
.expected {
  margin-right: 15px;
  stroke: green;
}
</style>
<body>
<template id="target-template">
  <svg width="50" height="50">
    <rect x="0" y="0" width="50" height="50" />
  </svg>
</template>
<script src="resources/interpolation-test.js"></script>
<script>
assertInterpolation({
  property: 'stroke-opacity',
  from: neutralKeyframe,
  to: '0.4',
}, [
  {at: -0.3, is: '0.66'},
  {at: 0, is: '0.6'},
  {at: 0.3, is: '0.54'},
  {at: 0.6, is: '0.48'},
  {at: 1, is: '0.4'},
  {at: 1.5, is: '0.3'},
]);

assertInterpolation({
  property: 'stroke-opacity',
  from: 'initial',
  to: '0.4',
}, [
  {at: -0.3, is: '1'},
  {at: 0, is: '1'},
  {at: 0.3, is: '0.82'},
  {at: 0.6, is: '0.64'},
  {at: 1, is: '0.4'},
  {at: 1.5, is: '0.1'},
]);

assertInterpolation({
  property: 'stroke-opacity',
  from: 'inherit',
  to: '0.4',
}, [
  {at: -0.3, is: '0.92'},
  {at: 0, is: '0.8'},
  {at: 0.3, is: '0.68'},
  {at: 0.6, is: '0.56'},
  {at: 1, is: '0.4'},
  {at: 1.5, is: '0.2'},
]);

assertInterpolation({
  property: 'stroke-opacity',
  from: 'unset',
  to: '0.4',
}, [
  {at: -0.3, is: '0.92'},
  {at: 0, is: '0.8'},
  {at: 0.3, is: '0.68'},
  {at: 0.6, is: '0.56'},
  {at: 1, is: '0.4'},
  {at: 1.5, is: '0.2'},
]);

assertInterpolation({
  property: 'stroke-opacity',
  from: '0',
  to: '1'
}, [
  {at: -0.3, is: '0'},
  {at: 0, is: '0'},
  {at: 0.3, is: '0.3'},
  {at: 0.6, is: '0.6'},
  {at: 1, is: '1'},
  {at: 1.5, is: '1'},
]);
</script>
</body